“嫦娥三号”于2013年12月14日21时11分降落在距离地球38万公里的月球上

发布时间：2017-04-14 00:57 │ 来源：www.tikuol.com

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问题：

“嫦娥三号”于2013年12月14日21时11分降落在距离地球38万公里的月球上，中国成为继苏联、美国之后的第三个在月球成功实现探测器软着陆的国家。着陆前“嫦娥三号”曾在离月面100ｍ处悬停避障，然后缓速下降，离月面4ｍ时，7500N变推力发动机关机，“嫦娥三号”做自由落体运动降落在月球虹湾以东地区（19.51Ｗ，44.12Ｎ），已知月表重力加速度为地表重力加速度的六分之一，下列说法正确的是（g取9.8ｍ／s²）

A．若悬停时“嫦娥三号”的总质量为kg，则变推力发动机的推力约为2450Ｎ

B．“嫦娥三号”落月点的北边十几米处有一个大撞击坑，假如悬停时“嫦娥三号”在撞击坑的正上方，为避障姿态控制发动机先向南喷气，后向北喷气再次悬停在落月点正上方

C．变推力发动机关机后，同样的着陆速度相当于从离地球表面m处落下

D．变推力发动机关机后，同样的着陆速度相当于从离地球表面m处落下

考点：万有引力定律的其他应用

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下面是5个中学生遇到的难题和某报专栏编辑给他们的建议。请将问题与建议配对。

( )71. Sometimes I get angry easily and shout at my friends. That makes them think I’m not friendly to them.
( )72. In my teachers’ eyes, I am a good student. Both my classmates and my parents also think so. No one knows what my problem is. I often feel worried about my schoolwork.
( )73. My parents never allow me to play computer games at all. They want me to study all day and do well in my exams. I feel unhappy.
( )74. I want to join in some after-school activities, but my parents think they are too dangerous and don’t allow me to go out alone.
( )75. My mother gets me to take piano lessons. She makes it a rule that I must practice two hours a day. I really try my best, but I just can’t play well.

A. Let your parents know you will not be alone. Also, you can ask a teacher to talk to your parents about the after-school activities.
B. Don’t worry. You can still have some indoor sports. They are also fun.
C. Don’t worry, even great piano players have to practice. Hard work and a lot of practice are the only way to become a good piano player.
D. When you feel angry you should stop talking and count from one to ten or walk away until you keep quiet.
E. Tell your friends how you are feeling. You are in a new class, but you still need their friendship. Also, you can make new friends.
F. Don’t worry. Everybody worries about their schoolwork, even those students like you who study well. Find a hobby or a sport to help you relax for a while.
G. Tell your parents that many kids play computer games and do well at school, too. Ask them to let you play computer games for a short time on weekends.

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泻白散与清骨散的组成中均含有的药物是

A．桑白皮

B．地骨皮

C．牡丹皮

D．五加皮

E．茯苓皮

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以下关于前文本的描述，错误的是（）。

A.文本生成之前的所有文化文本组成的网络

B.文本生成时受到的全部文化语境的压力

C.前文本是特指的，是指某一个文本

D.整部电影史是一部电影生成的前文本

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线路发生改造或检修后导致线路长度、铁塔基数等基础数据发生变化时，不得通过“（）”操作，而应通过“（）”操作修改基础数据。

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